Tme limit overload switch



July 19, 1932.

c. H. RIPPL I 1,868,256

TIME LIMIT OVRLOAD SWITCH Filedxmay 11 1929 i A2 Sheets-Sheet l Lamento?? w( Ma-MW July 19, 1932. c. H. RIPPL. L368256 TIME LIMIT OVERLOAD SWITCH Filed May 1l, 1929 2 Sheets-Sheet 2 5' of switch.

Patented July v19, `1932 UNITED STATES PATENT OFFICE CHARLES H.

RIPPL, OF EAST CLEVELAND,.OHIO, ASSIGNOR TO THE CLARK CONTROLLER COMPANY, F CLEVELAND, OHIO, A. GORPORATION 0F OHIO TIME LIMIT OVERLOAD SWITCH Application filed May 11` 1929. Serial No. 362,269.

This invention relates to time limit overload switches, the same having particular utility when the switch is used as a relay, though not necessarily confined to that type One of the objects of the invention is to provide a time limit overload switch which will operate satisfactorily at moderate overloads with the time limit effect and instantaneously at a predetermined heavier overload with a wide`range of adjustment of the current values at which the switch will operate with the time limit effect.

A further object is to provide a switch wherein the time limit effect is obtained through the retarded movement of a plunger in a chamber containing oil or other -suitable fluid, which the plunger -mustdisplace in its travel under the action of the magnetic `field to bring about the actuation of the switch, the chamber being arranged for ad-y j ustment axially of the magnet and preferably within a hollow portion of the magnet, the whole being so constructed that the overload value of the current at which the switch will operate with the time limit effect can be widely adjusted without materially. varying the overload value of the current which will cause instantaneous operation.

' VStill further, the invention aims to accomplish the above objects with a very compact and efficiently operating switch structure, together with a maximum safety against leakage of the oil or other fluid from the chamber containing the plunger.

The above and other objects are attained by the present invention which may be here brieflyl summarized as consisting in certain novel details of construction and combinations and arrangements of parts which will be described in the specication and set forth in the appended claims.

In the accompanying sheets of drawings showing an embodiment ofthe invention which operates with high efficiency,

Fig. 1 is a side elevation of the switch' in the form of a relay, in its normal closed po-v sition,

Fig. 2 is a similar view, on a reduced scale, showing the switch open;

Fig. 3 is a fragmentary view showing the central part of the overload magnet with the chamber containing the plunger adjusted to a position other than illustrated in Figs. 1 and 2, the chamber being lowered with respect to the core or plug at the top of the magnet so as to increasevthe current value at which the switch will be opened with the time limit effect; l y

Fig. 4 is a front View of the switch on substantially the scale of Fig. 2;

gig. 5 is a top plan view of the switch; an

j Fig. 6 is a transverse sectional view sub# stantially on the line 6`-6, the parts being shown on the reduced scale of F igs.- 2, 4 and paratus are mounted. Mounted on the front` of the base 10 is an overload magnetcoil 11 supported in a frame including in f this instance an L-shaped piece 12 of magnetic material, such as iron, 'secured .by one or more screws13 tothe base, thisp'iece 12 forming the( bottom and the outer side of the frame. The top of the frame consists preferabl of @a casting 14 of non-magnetic materia,

such as bronze,'which is secured by a screw `15 to the outer top portion of the frame member 12 and by a screw 16 tothe base 10.

The non-magnetic frame member 14 is provided adjacent the base 10 with a pair of spaced ears 14a and in these ears is mounted a pivot pin 17 for the movable switch member 18. The movable switch member 18 includes a body portion 18a of insulating material to the lower` part of which is secured a stamping 18,?) preferably of non-magnetic material having ears 18c mounted on the pivot pin 17. This switch member is biased toward closed position by a spring-, in this by screws or bolts 24 to the base 10. As the 5 is a stamping 20 extending to opposite sides -of the/member 18a and having at its ends contacts 21 which are adapted to engage normally stationary contacts 22 secured, in this instance, to the upper ends of the spring iingers 23, the lower ends of which are secured stamping 2O with its two contacts 21 constitutes a bridging contact, the stamping may have a slight` swivel action at the center so that the two contacts 21 will bear with equalized pressure on the contacts 22. The last named contacts 22 are mounted on the spring fingers 23 so as to avoid shock in the closure of the switch and to otherwise improve the action of the switch in the closing and opening movements of the movable switch member. When the switch is closed by the action of the spring 19, the contacts 22 yield backward slightly with both pairs of contacts held in engagement under the same pressure, and when the switch opens the contacts 22 move forward slightly. It will be understood that conductors (not shown) for the circuit to be opened and closed by the switch will be connected to the bolts 24 at the rear of the base 10.

As aforemenioned, the switch is closed and held inpclosed osition by the spring 19. It is adapted to e opened by an armature 26 when the armature is attracted and pulled down against the core, Ato vbe shortly explained, of the magnet.y This armature,

which of course is formed of magnetic material, is fulcrumed on the outer upper end 12a of the frame member 12, this portion being somewhat wedge-shaped and fitting into an offset recess in the armature, as best illustrated in Fig. 1. The armature is normally held in,its olf or released position, illustrated in Fig. 1, by a spring 27 which in this instance is attached at one end to the youter end of the armature just outwardly of the upright side of the magnet frame member 12 and at its other end to pin 28 on said frame member.

When the armature is in its released posii tion, as in Fig. 1, the inner end of the armature bears against an abutment 29 carried by the switch member 18 a short distance above its lower pivoted end, the armature thus asslstingthe spring 19 in holding the switch closed. But when the armature is -attracted 1t engages a second abutment in the form of an outwardly projecting lip 30 at the bottom of the stamping 186 forming apart of the switch member 18 and opens the switch quickly or with a snap action. Between the abutments 29 and 30, the armature has a free movement and when it engages the lower abutment 30 it strikes`it with a suicient blow to quickly open the switch in the manner just stated. Of course, as long as the magnetic pull which caused the armature to open the switch is maintained on the armature, it will hold the switch open in the position shown in Fig. 2. But when the magnet is deenergized or when the magnetic pull is `decreased suiiiciently, the spring 27 will restore the armature to its normal position and the switch will be closed.

The magnet coil 11 surrounds an insulating spool 25 composed of top and bottom members and a hollow barrel. Extending into the coil and, in fact, in the hollow barrel of the spool is a core 31 formed of magnetic material, the core being, in this instance, in the form of a hollow plug which extends through and has threaded engagement with the non-magnetic top member 14 of the magnet frame. In this plug there is a hollow chamber or space 31a, extending from the lower or open end of the plug to near the top thereof,`as clearly shown in Figs. 1 to 3. The upper end of the plug is given a hexagonal or other suitable shape so that it can be conveniently screwed into a place for assembly purposes by a wrench, but when the plug is once in place its position is not ordinarily varied. f

Extending up centrally through the bottom of the ma et and having threaded engagement with the bottom of the member 12 of the magnet frame is a vertically adjustable chamber and core assembly including a chamber 32 formed of non-magnetic material and adapted to contain oil or other suitable fluid. The chamber 32 is in the form of a hollow cylinder closed at both ends. the lower end being closed by a screw plug 32a which, when screwed in place, is preferably sealed by soldering or otherwise to make the chamber absolutely leak-proof. Adapted to travel lengthwise of this chamber is a plunger 33 of magnetic material. This lis likewise cylindrical in form, its external diameter being just slightly less than the internal diameter of the chamber 32. The plunger has an opening extending therethrough from end lto en d and through this passageway the major portion of the oil passes from one end of the lunger tothe other when the oil is displaced y the return movement of the plunger to the lower part of the chamber. A `ball check valve 34 controls this passageway so that the upward movement of the pull of the magnet will be, relatively slow (the passageway then being closed by the ball valve) and its downward movement, when the ma et is deenergized will be relatively fast the ball valve then being unseated) The chamber is adapted to be adjusted up and down to vary the current value which will cause the switch tol open with a time limit effect, and, for thatreason, the outer wall of the chamber has fitted around it a 1,see,256

sleeve 35, preferably but not necessarily of magnetic material, threaded for substantially its full length as shown. The sleeve 35, which is held from endwise movement on the chamber 32, permits of a considerable adjustment of the chamber and plunger assembly axially of the magnet. It is not essential that the threads be formed on a separate sleeve but this is done in this instance for convenience of manufacture only. The lower end of the sleeve 35 is somewhat enlarged, as shown at 35a, and this part is hexagonal or otherwise shaped to receive a wrench or adjusting tool which will enable the position of the chamber and plunger assembly tol be varied axially of the magnet. When it has been adjusted to the right position, it can be locked in that position by a nut 36 which engages the threads of the sleeve 35 and is adapted to be screwed up against the lower 'side of the magnetic frame memberl 12, as

illustrated in Figs. 1 to 3.

When the magnet is energized by a current of predetermined value (below the current value which causes instantaneous operation) 'the switch is not at once opened, but the pull of the magnet will cause the plunger to travel upwardly in the chamber 32 at a predetermined rate, and when it reaches a position more or less close to the upper end of the chamber, the reluctance of the magnetic field is decreased to the extent that there is now a sufficient attractive force exerted on the armature to pull it down against the top of the plug 31 and open the switch. Il the overload is only temporar the switch will not be opened, but if it contlnues until the plunger reaches the given position above stated, the switch will be opened. Thus, for a moderate predetermined overload a certain time will elapse between the energization of the magnet at this overload value of current and the opening of the switch, but if a severe overload occurs, and, in fact, when the current value exceedsacertain predetermined amount, there is a ysuihcient pull exerted on the armature to attract it without requiring any decrease in the reluctance of the magnetic path by the upward travel of the plunger. In other words, the switch is then opened instantly.

The core or plug 31 being hollow, the upper part of the chamber can be moved well up into the core or it may be lowered wholly or partially out of the same, as will be seen by comparison of Figs. 1 and 3. B thus raising or lowerin the chamber and p unger assembly, I am a le to vary, over a very wide ran e, the value of the current which will cause t e switch to open with the ltime limit etl'ect. The more the chamber and plunger assembly is lowered the higher this current value becomes, and the more it is elevated, the lower it becomes. By making the core hollow so that the chamber can be adjusted up into it, I am ablelto obtain this adjustment without requiring a large and bulky construction, that is to say, I secure a de ree of compactness otherwise not obtama le. Furthermore,

what is equally, if not more important, I find that with this construction there is such a distribution of magnetic material that the overload value of the current at which the switch will open instantaneously is not materially aii'ected by the adjustment of the chamber. These advantages, coupled with the eilicient action of the switch proper explained earlier in the speciication,l and the fact that leakage of the Huid 'inthe chamber is absolutely prevented, render the present improvements quite important, articularly when ap- =`plied to timev limit over oad relays.

While I have shown'the Vpreferred construction, I do not desire to be confined to the precise details of construction or ar-A rangement, but aim in my claims to cover all modications which do not involve a departure from the spiritv and scope of the invention.

Having -thus .described my invention, I"

claim:

1. In `a time limit switch, stationary and movable switch members, a magnet for operating the switch and provided with a hollow core of magnetic material, and a chamber adapted to extend into the core, the chamber"l containing a l'luid and a plunger adapted to be moved toward the core by the action of the magnetic eld.

2. Ina time limit switch, stationary and movable switch members, .a magnet for operating the switch, there being arranged centrally of the coil of the magnet a hollow core formed of magnetic material, and a chamber formed of non-magnetic material and containing a plunger movable longitudinally thereof, the core and chamber being relatively adjustable so that the chamber may be caused to extend different distances into the core.

3. In a time limit switch, movable and staf tionary switch members, a magnet for operjustably supported so that it may 'be moved vayin distancesinto the core, the chamber being ormed of non-magnetic material and the plunger of magnetic material.Y i

4. Ina time limit switch, stationary and movable switch members, a. magnet for operating the switch and comprising a coll, a frame, a core mounted in one part of the frame, and a chamber mounted in another part of the frame, the core and chamberbeing telescopically arranged and being relatively adjustable and the chamber containing a plunger movable lengthwise thereof by the action oi the magnetic field.

5. In a time limit switch, stationary and movable switch'members, a magnet for operating the switch comprising a coil, a frame, a hollow core mounted in the top of the frame, and a chamber adjustably mounted in the bottom of the frame and extending u into the coil and adapted to be extended di erent distances into the core, the chamber containing a plunger movable toward the core by the action of the magnetic field.

In testimony whereof I hereunto aix my signature.

CHARLES H. RIPPL. 

